I am unable to remotely debug a webapp.

The app sits on [10.3.50.xxx] and the vs.net is installed on [10.3.8.xxx].
I can open and load the remote web, even build it. When I hit debug, I get the following error message:
"Error while trying to run project. Unable to start debugging on the web server. Could not start ASP.NET or ATL debugging.
Verify that ASP.NET or ATL Server is correctly installed on the server.
Any ideas?
Thanks, Dirk